This invention relates in general to communication systems and devices and in particular to communication devices having a time of day clock.
A pager user who is subscribed to a paging system operator which provides for roaming services can use his/her pager when traveling between different cities, and in some cases, between different states or countries. Such roaming capability allows the pager user to receive messages when traveling between distant locations.
Some currently available pagers provide the user with many features including a time of day clock feature. The time of day (also referred to as real time clock information) and sometimes date information is typically displayed on the pager""s display when the pager is turned on. Some pagers also provide for other features such as alarm features which let the pager user set the pager so that an alarm is generated at a certain time and date. At the selected time, the pager will typically either emit an audible alert or vibrate, depending on how the pager""s alert mode is set by the user. It is known in the art to automatically adjust the pager""s time of day clock when a roaming pager enters a new paging system coverage area operating in a different time zone than the pager""s home paging system""s time zone.
One example of an automatic time zone adjustment to a portable receiver""s time of day clock is included within U.S. Pat. No. 5,089,814 to DeLuca et al. assigned to the assignee of the present invention. The automatic time zone adjustment feature automatically adjusts the pager""s time of day clock to reflect the local time. This is useful when a pager user roams between different time zones, since the time of day clock is automatically adjusted to reflect the current time of day found in the pager""s current system.
Some of the newer paging protocols such as the well known FLEX(trademark) (a trademark of Motorola, Inc.) paging protocol transmit time, date and time zone information as part of the paging protocol which can be used to update the pager""s real-time clock information. This information is transmitted to the pager via block information words which are part of the paging protocol and which include local channel ID having time zone information, and real time and date information.
A problem however occurs when a user is roaming between different time zones (between his home time zone and one or more different time zones) and has set an alarm on his pager to alert him/her at a certain time.
A need thus exists for a method and apparatus which can provide effective and reliable alarms.